Roll a ball camera with rotating by a mouse?

With the Unity tutorial I created a camera that follows a player (ball), but it’s only follows in one rotation. I wanna create a camera that not only follows a player, but rotates around a player with mouse. Here’s my code:
public GameObject player;
private Vector3 offset;
public int speed;

    private void Start()
    {
        offset = transform.position;
        Cursor.visible = false; //Hides cursor.
    }

    private void Update()
    {
        transform.LookAt(player.transform);
        transform.RotateAround(player.transform.position, Vector3.up, Input.GetAxis("Mouse X") * speed);
    }

Thanks in advance!

Hello;

I am getting an Error - Assets\Camera_Mouse.cs(16,105): error CS1513: } expected

I think it is a } some where / or one is missing …I am new to this SO I could really use some help here

Thanks

  Jody